A novel behavioral model using three-layer time-delay feed-forward neural networks （TDFFNN）is adopted to model radio frequency （RF）power amplifiers exhibiting memory nonlinearities. In order to extract the paramet...A novel behavioral model using three-layer time-delay feed-forward neural networks （TDFFNN）is adopted to model radio frequency （RF）power amplifiers exhibiting memory nonlinearities. In order to extract the parameters, the back- propagation algorithm is applied to train the proposed neural networks. The proposed model is verified by the typical odd- order-only memory polynomial model in simulation, and the performance is compared with different numbers of taped delay lines（TDLs） and perceptrons of the hidden layer. For validating the TDFFNN model by experiments, a digital test bench is set up to collect input and output data of power amplifiers at a 60 × 10^6 sample/s sampling rate. The 3.75 MHz 16-QAM signal generated in the vector signal generator（VSG） is chosen as the input signal, when measuring the dynamic AM/AM and AM/PM characteristics of power amplifiers. By comparisons and analyses, the presented model provides a good performance in convergence, accuracy and efficiency, which is approved by simulation results and experimental results in the time domain and frequency domain.展开更多
There are two kinds of unbalance vibrations—force vibration and displacement vibration due to the existence of unbalance excitation in active magnetic bearings（AMB） system. And two unbalance compensation methods—c...There are two kinds of unbalance vibrations—force vibration and displacement vibration due to the existence of unbalance excitation in active magnetic bearings（AMB） system. And two unbalance compensation methods—closed-loop feedback and open loop feed-forward are presented to reduce the force vibration. The transfer function order of the control system directly influencing the system stability will be increased when the closed-loop method is adopted, which makes the real-time compensation not easily achieved. While the open loop method would not increase the primary transfer function order, it provides conditions for real-time compensation. But the real-time compensation signals are not easy to be obtained in the open loop method. To implement real-time force compensation, a new method is proposed to reduce the force vibration caused by the rotor unbalance on the basis of AMB active control. The method realizes real-time and on-line force auto-compensation based on H∞ controller and one novel feed-forward compensation controller, which makes the rotor rotate around its inertia axis. The time-variable feed-forward compensatory signal is provided by a modified adaptive variable step-size least mean square（VSLMS） algorithm. And the relevant least mean square（LMS） algorithm parameters are used to solve the H∞ controller weighting functions. The simulation of the new method to compensate some frequency-variable and sinusoidal signals is completed by MATLAB programming, and real-time compensation is implemented in the actual AMB experimental system. The simulation and experiment results show that the compensation scheme can improve the robust stability and the anti-interference ability of the whole AMB system by using H∞ controller to achieve close-loop control, and then real-time force unbalance compensation is implemented. The proposed research provides a new control strategy containing real-time algorithm and H∞ controller for the force compensation of AMB system. And the stability of the control system is finally improved.展开更多
Feed-animal balance is the key technique on the grassland ecosystem management,and attracts widespread attention in the world.Many studies have been conducted by former researchers,and most of their efforts were inten...Feed-animal balance is the key technique on the grassland ecosystem management,and attracts widespread attention in the world.Many studies have been conducted by former researchers,and most of their efforts were intended to keep the balance of feed-animal.However,there are still much more issue needed to be studied in details on the face of grassland degeneration and animal husbandry sustainable development.The author analyzed the feed-animal balance research progress,including the concept of stocking rate and its practical management techniques,especially on the stocking rate calculation methods.In addition,the social and economy effects on feed-animal balance were also discussed during the progress of improving the development of pastoral economy.In order to achieve feed-animal balance more effectively,it was concluded that the focus must be shift from only on animal number to the grassland quality,and it's necessary to strengthen market tax control.展开更多
Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic disto...Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion （THD） is greatly reduced. The weights of filter are adjusted on-line according to the control error by using least-mean-square （LMS） algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator （AFC） control scheme展开更多
This paper describes the application of principal component analysis (PCA) and artificial neural network (ANN) to predict the air pollutant index (API) within the seven selected Malaysian air monitoring stations in th...This paper describes the application of principal component analysis (PCA) and artificial neural network (ANN) to predict the air pollutant index (API) within the seven selected Malaysian air monitoring stations in the southern region of Peninsular Malaysia based on seven years database (2005-2011). Feed-forward ANN was used as a prediction method. The feed-forward ANN analysis demonstrated that the rotated principal component scores (RPCs) were the best input parameters to predict API. From the 4 RPCs, only 10 (CO, O3, PM10, NO2, CH4, NmHC, THC, wind direction, humidity and ambient temp) out of 12 prediction variables were the most significant parameters to predict API. The results proved that the ANN method can be applied successfully as tools for decision making and problem solving for better atmospheric management.展开更多
The local gas-flow behavior is almost unknown for low pressure plasma systems, except parallel plate reactors for semiconductor purposes. To overcome this lack of knowledge, this study starts with the influence invest...The local gas-flow behavior is almost unknown for low pressure plasma systems, except parallel plate reactors for semiconductor purposes. To overcome this lack of knowledge, this study starts with the influence investigation of the gas feed-in systems technical layout on the homogeneity of the gas supply for large volume plasma enhanced chemical vapor deposition (PECVD) chambers. Computational fluid dynamics (CFD) simulations are used as a tool to determine velocity and pressure distribution inside the gas feed-in pipe as well as in the PECVD-chamber itself. The parameters varied were: flow rate, pipe length, number of holes, hole diameter and aspect ratio of the pipe section. The calculated pressure values are compared with the experimentally measured ones to validate the simulation results. An excellent conformity of the calculated and measured pressures is observed. With the aim to evaluate the homogeneity of gas distribution through the pipe holes the nonuniformity coefficient (Φ) was created. The results show the influence of each layout parameter in the homogeneity of the gas distribution. Hence in future correct technical layouts of gas feed-in systems can easily be applied. With these results construction guidelines has been formulated.展开更多
Feed-forward gene transcriptional regulatory networks, as a set of common signal motifs, are widely distributed in the biological systems. In this paper, the noise characteristics and propagation mechanism of various ...Feed-forward gene transcriptional regulatory networks, as a set of common signal motifs, are widely distributed in the biological systems. In this paper, the noise characteristics and propagation mechanism of various feed-forward gene transcriptional regulatory loops are investigated, including （i） coherent feed-forward loops with AND-gate, （ii） coherent feed-forward loops with OR-gate logic, and （iii） incoherent feed-forward loops with AND-gate logic. By introducing logarithmic gain coefficient and using linear noise approximation, the theoretical formulas of noise decomposition are derived and the theoretical results are verified by Gillespie simulation. From the theoretical and numerical results of noise decomposition algorithm, three general characteristics about noise transmission in these different kinds of feed-forward loops are observed, i） The two-step noise propagation of upstream factor is negative in the incoherent feed-forward loops with AND-gate logic, that is, upstream factor can indirectly suppress the noise of downstream factors, ii） The one-step propagation noise of upstream factor is non-monotonic in the coherent feed-forward loops with OR-gate logic, iii） When the branch of the feed-forward loop is negatively controlled, the total noise of the downstream factor monotonically increases for each of all feed-forward loops. These findings are robust to variations of model parameters. These observations reveal the universal rules of noise propagation in the feed-forward loops, and may contribute to our understanding of design principle of gene circuits.展开更多
In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded,...In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.展开更多
The coagulation bath system of carbon fiber precursor is a complicated and multivariable coupling system. Based on the model of industrial production,the full dynamic decoupling control of the coagulation bath system ...The coagulation bath system of carbon fiber precursor is a complicated and multivariable coupling system. Based on the model of industrial production,the full dynamic decoupling control of the coagulation bath system of carbon fiber precursor is achieved in combination with multivariable feed-forward-like decoupling and proportional-integral-differential( PID) control. Compared with the conventional PID decoupling control,the experiment results show that the proposed method has a better control effect. The use of the controller can achieve complete decoupling of three parameters from coagulation bath system. The method should have great applications.展开更多
In the oil industry, the productivity of oil wells depends on the performance of the sub-surface equipment system. These systems often have problems stemming from sand, corrosion, internal pressure variation, or other...In the oil industry, the productivity of oil wells depends on the performance of the sub-surface equipment system. These systems often have problems stemming from sand, corrosion, internal pressure variation, or other factors. In order to ensure high equipment performance and avoid high-cost losses, it is essential to identify the source of possible failures in the early stage. However, this requires additional maintenance fees and human power. Moreover, the losses caused by these problems may lead to interruptions in the whole production process. In order to minimize maintenance costs, in this paper, we introduce a model for predicting equipment failure based on processing the historical data collected from multiple sensors. The state of the system is predicted by a Feed-Forward Neural Network (FFNN) with an SGD and Backpropagation algorithm is applied in the training process. Our model’s primary goal is to identify potential malfunctions at an early stage to ensure the production process’ continued high performance. We also evaluated the effectiveness of our model against other solutions currently available in the industry. The results of our study show that the FFNN can attain an accuracy score of 97% on the given dataset, which exceeds the performance of the models provided.展开更多
The identification of contamination sources within the food chain with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs), (“dioxins”), and PCBs is difficult and complex. PCDD/PCDF ...The identification of contamination sources within the food chain with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs), (“dioxins”), and PCBs is difficult and complex. PCDD/PCDF can be formed as unintentional compounds in a number of chemical processes as well as in almost every combustion process. PCBs were intentionally produced chemicals that were manufactured for decades before the ban in marketing and use in many countries around 1985. The pattern of occurrence can change from the original source in particular via feedingstuffs to food of animal origin as result of bioaccumulation. A number of examples illustrate the challenging detective work and key scientific aspects for identification of the sources, for support of the risk management and for performance of monitoring programs. The contamination of milk and milk products in European countries with dioxins was caused by compound feeds containing citrus pulp pellets from Brazil which had high dioxin levels as a result of the use of heavily contaminated lime used for neutralization. The Belgian dioxin crisis was caused by a feed additive heavily contaminated with PCBs which were discharged into a recycled fat used in the production of animal feed. Guar gum from India was contaminated with sodium pentachlorophenate and dioxins. Clay was found to be possibly highly contaminated with dioxins possibly formed by geothermal processes over time;use of such clay as feed additive or for human intake led to elevated dioxin levels in food and humans. Bioanalytical screening in combination with comprehensive physicochemical investigations led to the detection of brominated flame retardants and brominated dioxins in a feed additive. Buffalo milk was contaminated in Italy presumably caused by illegal deposition of waste. High PCB levels in fuel oil for drying of breadcrumb used as a feed ingredient caused a major dioxin crisis with pork meat in Ireland. Fatty acids for technical purposes originating from a biodiesel company were used for production of feed fat which contaminated parts of the food chain in Germany. In addition to effects on human and animal health these incidents also have serious economic consequences which could be mitigated by more frequent control on food and feed. Addressing both these issues, the European Community has developed a strategy to reduce the presence of dioxins and PCBs in the environment and in feed and food comprising the establishment of maximum and action levels.展开更多
A kind of second order algorithm--recursive approximate Newton algorithm was given by Karayiannis. The algorithm was simplified when it was formulated. Especially, the simplification to matrix Hessian was very reluct...A kind of second order algorithm--recursive approximate Newton algorithm was given by Karayiannis. The algorithm was simplified when it was formulated. Especially, the simplification to matrix Hessian was very reluctant, which led to the loss of valuable information and affected performance of the algorithm to certain extent. For multi layer feed forward neural networks, the second order back propagation recursive algorithm based generalized cost criteria was proposed. It is proved that it is equivalent to Newton recursive algorithm and has a second order convergent rate. The performance and application prospect are analyzed. Lots of simulation experiments indicate that the calculation of the new algorithm is almost equivalent to the recursive least square multiple algorithm. The algorithm and selection of networks parameters are significant and the performance is more excellent than BP algorithm and the second order learning algorithm that was given by Karayiannis.展开更多
Stribeck effect is regarded as the most important feed-axis friction characteristics. According to the relationship between friction and lubrication,a rapid technology for feed-axis lubrication condition evaluation of...Stribeck effect is regarded as the most important feed-axis friction characteristics. According to the relationship between friction and lubrication,a rapid technology for feed-axis lubrication condition evaluation of computer numerical control( CNC) machine tools based on soft sensor is proposed. To obtain its state information,the static friction force,Coulomb friction force,and viscous coefficient are used as the key parameters of the soft sensor for tread analysis. Then the various amplitude and velocity triangular wave test curve, and a precise nonlinear model identification method are presented. The results of the experiments analysis show that this method is feasible and reliable for evaluating feed-axis lubrication condition,which lays the foundation for on-line condition monitoring and reliability evaluation for feed-axis lubrication of machine tools.展开更多
The study evaluated the effects of a diet incorporating a mango-based feed on the technical-economic performance of milk production of Montbeliard cows at the end of lactation in a dairy farm in Bobo-Dioulasso, Burkin...The study evaluated the effects of a diet incorporating a mango-based feed on the technical-economic performance of milk production of Montbeliard cows at the end of lactation in a dairy farm in Bobo-Dioulasso, Burkina Faso. To do so, 14 cows were subjected to 3 diets, including an experimental diet incorporating mango (ED) in comparison to a balanced control diet (BCD) and to the feeding practice of the farmer (FCD) during 60 days. Results show that the average amount of milk milked per day from ED (10.93 ± 0.17 L) was significantly higher (p < 0.05) than BCD (8.80 ± 0.19 L) and RTA (5.39 ± 0.14 L). The conversion index of FPD (4.24 ± 0.14) was significantly higher (p < 0.05) than that of BCD (1.75 ± 0.19) and ED (1.26 ± 0.16). Average feed costs per liter of milk (FC/L) were significantly different (p (125.95 ± 4.56 FCFA), BCD (83.67 ± 6.36 FCFA) and ED (60.06 ± 5.49 FCFA). The average gross profit margins (GPM) were significantly higher and decreasing (p ,953 ± 5031 FCFA), BCD (167,157 ± 5831 FCFA) and FCD (74,188 ± 4185 FCFA). Mango feed can be used in the diet of dairy cows. Its use contributes to the reduction of production costs and the generation of substantial profits. The valorization of mango residues is an alternative for a greater availability of feed at lower cost for the animals. It could contribute to a better management of processing residues that pollute the environment and to the reduction of fruit flies that affect orchard yields through reinfestation. The increased use of mango in dairy cattle feed should be encouraged.展开更多
基金The National Natural Science Foundation of China(No.60621002)the National High Technology Research and Development Pro-gram of China(863 Program)(No.2007AA01Z2B4).
文摘A novel behavioral model using three-layer time-delay feed-forward neural networks （TDFFNN）is adopted to model radio frequency （RF）power amplifiers exhibiting memory nonlinearities. In order to extract the parameters, the back- propagation algorithm is applied to train the proposed neural networks. The proposed model is verified by the typical odd- order-only memory polynomial model in simulation, and the performance is compared with different numbers of taped delay lines（TDLs） and perceptrons of the hidden layer. For validating the TDFFNN model by experiments, a digital test bench is set up to collect input and output data of power amplifiers at a 60 × 10^6 sample/s sampling rate. The 3.75 MHz 16-QAM signal generated in the vector signal generator（VSG） is chosen as the input signal, when measuring the dynamic AM/AM and AM/PM characteristics of power amplifiers. By comparisons and analyses, the presented model provides a good performance in convergence, accuracy and efficiency, which is approved by simulation results and experimental results in the time domain and frequency domain.
基金supported by National Natural Science Foundation of China(Grant No.50437010)National Hi-tech Research and Development Program of China(863Program,Grant No.2006AA05Z205)Project of Six Talented Peak of Jiangsu Province,China(Grant No.07-D-013)
文摘There are two kinds of unbalance vibrations—force vibration and displacement vibration due to the existence of unbalance excitation in active magnetic bearings（AMB） system. And two unbalance compensation methods—closed-loop feedback and open loop feed-forward are presented to reduce the force vibration. The transfer function order of the control system directly influencing the system stability will be increased when the closed-loop method is adopted, which makes the real-time compensation not easily achieved. While the open loop method would not increase the primary transfer function order, it provides conditions for real-time compensation. But the real-time compensation signals are not easy to be obtained in the open loop method. To implement real-time force compensation, a new method is proposed to reduce the force vibration caused by the rotor unbalance on the basis of AMB active control. The method realizes real-time and on-line force auto-compensation based on H∞ controller and one novel feed-forward compensation controller, which makes the rotor rotate around its inertia axis. The time-variable feed-forward compensatory signal is provided by a modified adaptive variable step-size least mean square（VSLMS） algorithm. And the relevant least mean square（LMS） algorithm parameters are used to solve the H∞ controller weighting functions. The simulation of the new method to compensate some frequency-variable and sinusoidal signals is completed by MATLAB programming, and real-time compensation is implemented in the actual AMB experimental system. The simulation and experiment results show that the compensation scheme can improve the robust stability and the anti-interference ability of the whole AMB system by using H∞ controller to achieve close-loop control, and then real-time force unbalance compensation is implemented. The proposed research provides a new control strategy containing real-time algorithm and H∞ controller for the force compensation of AMB system. And the stability of the control system is finally improved.
基金The National Special Research Fund for Non-Profit Sector."Carrying Capacity and Livestock in Different Places"(200903060)"Re-search and Demonstration of Resources Optimization in Family Farmland"(201003019)+1 种基金"Research and Demonstration of Nurture of Natural Grassland and Used Technology in Semi-arid Farmland"(201303060)National Forage Industry Technological System(CARS-35)
文摘Feed-animal balance is the key technique on the grassland ecosystem management,and attracts widespread attention in the world.Many studies have been conducted by former researchers,and most of their efforts were intended to keep the balance of feed-animal.However,there are still much more issue needed to be studied in details on the face of grassland degeneration and animal husbandry sustainable development.The author analyzed the feed-animal balance research progress,including the concept of stocking rate and its practical management techniques,especially on the stocking rate calculation methods.In addition,the social and economy effects on feed-animal balance were also discussed during the progress of improving the development of pastoral economy.In order to achieve feed-animal balance more effectively,it was concluded that the focus must be shift from only on animal number to the grassland quality,and it's necessary to strengthen market tax control.
文摘Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion （THD） is greatly reduced. The weights of filter are adjusted on-line according to the control error by using least-mean-square （LMS） algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator （AFC） control scheme
文摘This paper describes the application of principal component analysis (PCA) and artificial neural network (ANN) to predict the air pollutant index (API) within the seven selected Malaysian air monitoring stations in the southern region of Peninsular Malaysia based on seven years database (2005-2011). Feed-forward ANN was used as a prediction method. The feed-forward ANN analysis demonstrated that the rotated principal component scores (RPCs) were the best input parameters to predict API. From the 4 RPCs, only 10 (CO, O3, PM10, NO2, CH4, NmHC, THC, wind direction, humidity and ambient temp) out of 12 prediction variables were the most significant parameters to predict API. The results proved that the ANN method can be applied successfully as tools for decision making and problem solving for better atmospheric management.
文摘The local gas-flow behavior is almost unknown for low pressure plasma systems, except parallel plate reactors for semiconductor purposes. To overcome this lack of knowledge, this study starts with the influence investigation of the gas feed-in systems technical layout on the homogeneity of the gas supply for large volume plasma enhanced chemical vapor deposition (PECVD) chambers. Computational fluid dynamics (CFD) simulations are used as a tool to determine velocity and pressure distribution inside the gas feed-in pipe as well as in the PECVD-chamber itself. The parameters varied were: flow rate, pipe length, number of holes, hole diameter and aspect ratio of the pipe section. The calculated pressure values are compared with the experimentally measured ones to validate the simulation results. An excellent conformity of the calculated and measured pressures is observed. With the aim to evaluate the homogeneity of gas distribution through the pipe holes the nonuniformity coefficient (Φ) was created. The results show the influence of each layout parameter in the homogeneity of the gas distribution. Hence in future correct technical layouts of gas feed-in systems can easily be applied. With these results construction guidelines has been formulated.
基金Project supported by the Fundamental Research Funds for the Central Universities,China(Grant Nos.2662015QC041 and 2662014BQ069)the Huazhong Agricultural University Scientific&Technological Self-innovation Foundation,China(Grant No.2015RC021)the National Natural Science Foundation of China(Grant Nos.11675060,91730301,11547244,and 11474117)
文摘Feed-forward gene transcriptional regulatory networks, as a set of common signal motifs, are widely distributed in the biological systems. In this paper, the noise characteristics and propagation mechanism of various feed-forward gene transcriptional regulatory loops are investigated, including （i） coherent feed-forward loops with AND-gate, （ii） coherent feed-forward loops with OR-gate logic, and （iii） incoherent feed-forward loops with AND-gate logic. By introducing logarithmic gain coefficient and using linear noise approximation, the theoretical formulas of noise decomposition are derived and the theoretical results are verified by Gillespie simulation. From the theoretical and numerical results of noise decomposition algorithm, three general characteristics about noise transmission in these different kinds of feed-forward loops are observed, i） The two-step noise propagation of upstream factor is negative in the incoherent feed-forward loops with AND-gate logic, that is, upstream factor can indirectly suppress the noise of downstream factors, ii） The one-step propagation noise of upstream factor is non-monotonic in the coherent feed-forward loops with OR-gate logic, iii） When the branch of the feed-forward loop is negatively controlled, the total noise of the downstream factor monotonically increases for each of all feed-forward loops. These findings are robust to variations of model parameters. These observations reveal the universal rules of noise propagation in the feed-forward loops, and may contribute to our understanding of design principle of gene circuits.
基金Supported by the National Key R&D Program of China(2016YFC1401900)the National Science Foundation of China(61173029,61672144)
文摘In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.
基金the Key Project of the National Nature Science Foundation of China(No.61134009)Program for Changjiang Scholars and Innovation Research Team in University from the Ministry of Education,China(No.IRT1220)+1 种基金Specialized Research Fund for Shanghai Leading Talents,Project of the Shanghai Committee of Science and Technology,China(No.13JC1407500)the Fundamental Research Funds for the Central Universities,China(No.2232012A3-04)
文摘The coagulation bath system of carbon fiber precursor is a complicated and multivariable coupling system. Based on the model of industrial production,the full dynamic decoupling control of the coagulation bath system of carbon fiber precursor is achieved in combination with multivariable feed-forward-like decoupling and proportional-integral-differential( PID) control. Compared with the conventional PID decoupling control,the experiment results show that the proposed method has a better control effect. The use of the controller can achieve complete decoupling of three parameters from coagulation bath system. The method should have great applications.
文摘In the oil industry, the productivity of oil wells depends on the performance of the sub-surface equipment system. These systems often have problems stemming from sand, corrosion, internal pressure variation, or other factors. In order to ensure high equipment performance and avoid high-cost losses, it is essential to identify the source of possible failures in the early stage. However, this requires additional maintenance fees and human power. Moreover, the losses caused by these problems may lead to interruptions in the whole production process. In order to minimize maintenance costs, in this paper, we introduce a model for predicting equipment failure based on processing the historical data collected from multiple sensors. The state of the system is predicted by a Feed-Forward Neural Network (FFNN) with an SGD and Backpropagation algorithm is applied in the training process. Our model’s primary goal is to identify potential malfunctions at an early stage to ensure the production process’ continued high performance. We also evaluated the effectiveness of our model against other solutions currently available in the industry. The results of our study show that the FFNN can attain an accuracy score of 97% on the given dataset, which exceeds the performance of the models provided.
文摘The identification of contamination sources within the food chain with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs), (“dioxins”), and PCBs is difficult and complex. PCDD/PCDF can be formed as unintentional compounds in a number of chemical processes as well as in almost every combustion process. PCBs were intentionally produced chemicals that were manufactured for decades before the ban in marketing and use in many countries around 1985. The pattern of occurrence can change from the original source in particular via feedingstuffs to food of animal origin as result of bioaccumulation. A number of examples illustrate the challenging detective work and key scientific aspects for identification of the sources, for support of the risk management and for performance of monitoring programs. The contamination of milk and milk products in European countries with dioxins was caused by compound feeds containing citrus pulp pellets from Brazil which had high dioxin levels as a result of the use of heavily contaminated lime used for neutralization. The Belgian dioxin crisis was caused by a feed additive heavily contaminated with PCBs which were discharged into a recycled fat used in the production of animal feed. Guar gum from India was contaminated with sodium pentachlorophenate and dioxins. Clay was found to be possibly highly contaminated with dioxins possibly formed by geothermal processes over time;use of such clay as feed additive or for human intake led to elevated dioxin levels in food and humans. Bioanalytical screening in combination with comprehensive physicochemical investigations led to the detection of brominated flame retardants and brominated dioxins in a feed additive. Buffalo milk was contaminated in Italy presumably caused by illegal deposition of waste. High PCB levels in fuel oil for drying of breadcrumb used as a feed ingredient caused a major dioxin crisis with pork meat in Ireland. Fatty acids for technical purposes originating from a biodiesel company were used for production of feed fat which contaminated parts of the food chain in Germany. In addition to effects on human and animal health these incidents also have serious economic consequences which could be mitigated by more frequent control on food and feed. Addressing both these issues, the European Community has developed a strategy to reduce the presence of dioxins and PCBs in the environment and in feed and food comprising the establishment of maximum and action levels.
文摘A kind of second order algorithm--recursive approximate Newton algorithm was given by Karayiannis. The algorithm was simplified when it was formulated. Especially, the simplification to matrix Hessian was very reluctant, which led to the loss of valuable information and affected performance of the algorithm to certain extent. For multi layer feed forward neural networks, the second order back propagation recursive algorithm based generalized cost criteria was proposed. It is proved that it is equivalent to Newton recursive algorithm and has a second order convergent rate. The performance and application prospect are analyzed. Lots of simulation experiments indicate that the calculation of the new algorithm is almost equivalent to the recursive least square multiple algorithm. The algorithm and selection of networks parameters are significant and the performance is more excellent than BP algorithm and the second order learning algorithm that was given by Karayiannis.
基金National Natural Science Foundation of China(No.51305324)
文摘Stribeck effect is regarded as the most important feed-axis friction characteristics. According to the relationship between friction and lubrication,a rapid technology for feed-axis lubrication condition evaluation of computer numerical control( CNC) machine tools based on soft sensor is proposed. To obtain its state information,the static friction force,Coulomb friction force,and viscous coefficient are used as the key parameters of the soft sensor for tread analysis. Then the various amplitude and velocity triangular wave test curve, and a precise nonlinear model identification method are presented. The results of the experiments analysis show that this method is feasible and reliable for evaluating feed-axis lubrication condition,which lays the foundation for on-line condition monitoring and reliability evaluation for feed-axis lubrication of machine tools.
文摘The study evaluated the effects of a diet incorporating a mango-based feed on the technical-economic performance of milk production of Montbeliard cows at the end of lactation in a dairy farm in Bobo-Dioulasso, Burkina Faso. To do so, 14 cows were subjected to 3 diets, including an experimental diet incorporating mango (ED) in comparison to a balanced control diet (BCD) and to the feeding practice of the farmer (FCD) during 60 days. Results show that the average amount of milk milked per day from ED (10.93 ± 0.17 L) was significantly higher (p < 0.05) than BCD (8.80 ± 0.19 L) and RTA (5.39 ± 0.14 L). The conversion index of FPD (4.24 ± 0.14) was significantly higher (p < 0.05) than that of BCD (1.75 ± 0.19) and ED (1.26 ± 0.16). Average feed costs per liter of milk (FC/L) were significantly different (p (125.95 ± 4.56 FCFA), BCD (83.67 ± 6.36 FCFA) and ED (60.06 ± 5.49 FCFA). The average gross profit margins (GPM) were significantly higher and decreasing (p ,953 ± 5031 FCFA), BCD (167,157 ± 5831 FCFA) and FCD (74,188 ± 4185 FCFA). Mango feed can be used in the diet of dairy cows. Its use contributes to the reduction of production costs and the generation of substantial profits. The valorization of mango residues is an alternative for a greater availability of feed at lower cost for the animals. It could contribute to a better management of processing residues that pollute the environment and to the reduction of fruit flies that affect orchard yields through reinfestation. The increased use of mango in dairy cattle feed should be encouraged.
